The invention relates in general to optical fiber adapters used to couple the connector of a first optical fiber cable to the connector of a second optical fiber cable. More particularly, the invention relates to an improved optical fiber adapter constructed as a one-piece tubular body with an alignment sleeve holder for capturing an alignment sleeve used to couple the ferrules of the two optical fiber connectors having the same diameter ferrules together, or alternatively provided with a stepped alignment sleeve for coupling optical fiber connectors having dissimilarly sized ferrules together.
The use and construction of optical fiber cables, and of optical fiber adapters, also referred to as couplers and more recently as build-outs, used for coupling optical fiber cables together is well known. Optical fiber cables are provided with optical fiber connectors at their ends, the connectors being one of the several known types of connectors, namely being either an SC, an ST(copyright), an FC, or an LC type of optical fiber connector. As is known, the SC, ST(copyright), and FC connectors are each provided with a 2.5 millimeter diameter ferrule which houses the optical fiber therein along a longitudinal axis of the connector, whereas the LC type of optical fiber connector is provided with a smaller 1.25 millimeter diameter ferrule.
The earliest types of optical fiber adapters were made using a simple coupler formed as a tubular body sized and shaped to allow an alignment sleeve to be passed therethrough, and in which the ferrules of the respective optical fiber connectors were placed so that the ferrules abutted one another within the alignment sleeve for the purpose of transmitting an optical signal from one optical fiber cable to the other. An example of such an early type of optical fiber coupling is disclosed in U.S. Pat. No. 5,082,345 to Cammons, et al., assigned to ATandT Bell Laboratories, a predecessor in interest to the assignee of this invention. The coupler of Cammons, et al. was adapted to couple two of the same type of optical fiber connectors together, but first required that the ferrule of a first one of the two connectors be passed into one of the ends of the alignment sleeve and then passing both the alignment sleeve and the ferrule together into the body of the adapter, whereupon the second ferrule was passed into the alignment sleeve. The device of Cammons was not provided with a means for separately securing the alignment sleeve within the body of the adapter, rather the ferrule of the first optical fiber connector was used for this purpose. Should the alignment sleeve of the xe2x80x9c345 patent have been placed in the adapter prior to one of the ferrules being passed therein, the first ferrule inserted into the adapter would have pushed the alignment sleeve out of the adapter, making the coupling of two optical fiber connectors quite difficult to accomplish in the field.
Another example of an early optical fiber adapter is disclosed in U.S. Pat. No. 5,212,752 to Stephenson, et al., also assigned to ATandT Bell Laboratories. The ""752 patent discloses a one-piece coupler used for coupling the ends of two optical fiber cables having an SC connector at their respective ends together. As with the patent to Cammons, et al., the ""752 patent was designed for use only with identically sized and shaped optical fiber connectors, in this instance SC connectors.
Accordingly, and as these two patents demonstrate, the problem that developed with these early optical fiber couplers was that as the number of differing types of optical fiber connectors increased, for example the SC, ST(copyright), FC, and LC family of optical fiber connectors now being widely used, the situation frequently arose in the field in which a first optical fiber cable having a first type of optical fiber connector was to be connected to a second optical fiber cable having a second type of optical fiber connector.
An early solution to the problem of coupling differing types of optical fibers together was addressed in U.S. Pat. No. 5,067,783 to Lampert, also assigned to ATandT Bell Laboratories. The ""783 patent to Lampert discloses an optical fiber connector build-out system having a first piece and a separate second piece which together formed the optical fiber adapter or build-out, and allowed an FC to ST(copyright) optical fiber connection, as well as ST(copyright) to ST(copyright), and FC to FC optical fiber connections. Although Lampert represented an advance in the art, the problem still persisted that as newer types of optical fiber connectors were developed, namely the LC and SC family of optical fiber connectors, there remained a continuing need to provide a universal system of coupling different types of optical fiber connectors together.
The universal optical fiber build-out system of U.S. Pat. No. 5,274,729 to King, et al. was developed to solve the ongoing problem of coupling the myriad of differing types of optical fiber connectors together, which patent is also assigned to ATandT Bell Laboratories. The ""729 patent to King, et al. allowed for the connection of SC, ST(copyright), and FC connectors to one another, as desired. More recently, in a patent application entitled xe2x80x9cUniversal Modular Optical Fiber Build-Outxe2x80x9d, filed in the U.S. Patent Office on Apr. 1st, 1999, U.S. patent application No. 09/282,926, and assigned to Lucent Technologies, Inc., the successor in interest to ATandT Bell Laboratories, a system was developed for coupling not only the larger 2.5 millimeter diameter ferrules of the SC, ST(copyright), and FC connectors to one another, but also allowing, for the first time, the smaller 1.25 millimeter diameter ferrules of the LC connectors to be quickly and easily coupled to optical fiber cables terminated with any one of the 2.5 millimeter diameter ferrules of the SC, ST(copyright), and FC connectors.
A problem that has arisen with the systems of Lampert, King, et al. and the aforementioned U.S. patent application is that in order to couple differing types of optical fiber connectors together, the optical fiber build-outs, or adapters, have been constructed of a first half for the first optical fiber connector, and of a separate second half for the second, potentially differing, type of optical fiber connector in order to allow for these couplings. This requires that two pieces be used to construct one optical fiber adapter, which construction is more costly in that it requires a larger parts inventory to accommodate xe2x80x9cstraightxe2x80x9d and xe2x80x9chybridxe2x80x9d couplings, and may also lead to an increase in labor costs needed to assemble these optical fiber build-outs/adapters in the field. In essence, a pair of connectors is required, which connectors must themselves first be connected to one another, in order to construct the adapter used to couple the two optical fiber cables together. Moreover, the fact that the two halves of the build-out are joined together to construct the build-out presents a potential point of structural weakness within the adapter.
What is needed, therefore, is a simple one-piece optical fiber adapter of a more robust design, one which is more rigid and thus more durable, and yet which is made of the same low-cost and high durability plastic materials of the aforementioned and more recent optical fiber build-out systems, the use of which will hopefully lead to lower inventory costs, lower manufacturing costs, and also require less labor in the field by eliminating the step of first constructing the adapter prior to connecting the ends of optical fiber cables/connectors together, and which will also fit into the same footprint, i.e. panel opening, formed in the mounting panels of the junction boxes and/or switch stations at which these panels are found, and at which the optical fiber cables are terminated and/or coupled together. Moreover, there is a need for such an improved one-piece tubular optical fiber adapter which can be used for coupling any one of the known types of optical fiber connectors to any other one of the known types of optical fiber connectors, be it an LC, SC, ST(copyright), and/or FC size and style connector, and which may be provided with an alignment sleeve, if so desired, and with a means for capturing the alignment sleeve within the adapter so that the alignment sleeve need not be handled in the field in what may be less than desirable job and/or field conditions when coupling optical fiber connectors together.
The present invention provides an improved one-piece optical fiber adapter which overcomes some of the design deficiencies of the known art. The one-piece optical fiber adapter of this invention provides a simple, efficient, and highly flexible device for coupling optical fiber cables together in the field quickly and easily.
Moreover, the relative simplicity of the optical fiber adapter of this invention, when contrasted to the known optical fiber adapters and/or build-outs, provides a greater degree of simplicity, reliability, durability, maintainability, and ease of use in the field when connecting similarly sized and shaped optical fiber connectors, as well as dissimilarly sized and shaped optical fiber connectors, together.
This invention attains this degree of flexibility, as well as simplicity in design and ease of use, by providing an elongate adapter comprised of a one-piece tubular body formed about a longitudinal axis, the body having a first end and a spaced second end. The first end of the adapter body is sized and shaped to receive a first optical fiber connector therein, and the second end of the body is sized and shaped to receive a second optical fiber connector therein. An elongate tubular alignment sleeve is positioned along the longitudinal axis of the body, and is held therein in a first snap fit for being secured within the body of the adapter so that when it is used for connecting optical fiber connectors together, they can be quickly and easily fastened to the respective ends of the adapter and their respective ferrules passed into the alignment sleeve without the need for handling the alignment sleeve in the field, i.e. by having to first pass the alignment sleeve over the ferrule of one of the connectors before passing the connector and the alignment sleeve together into the tubular body for connection to the ferule of the second optical fiber connector.
The invention thus comprises, in one embodiment, an elongate alignment sleeve holder positioned along the longitudinal axis of the adapter body and received within the adapter body in a second snap fit, the alignment sleeve being received within the alignment sleeve holder in the aforementioned snap fit along the longitudinal axis of the adapter. In this construction, the alignment sleeve holder is releasably held or captured within the tubular body of the adapter, with the alignment sleeve being separately and releasably captured within the alignment sleeve holder. In this embodiment of the invention, an alignment sleeve holder latching device is provided for retaining the alignment sleeve holder within the body in the second snap fit, the latching device comprising at least one elongate latch gate spaced from and extending in a lengthwise direction parallel to the axis of the adapter body, and at least one annular stop formed within the body and about the axis thereof, the stop being spaced from the at least one latch gate for defining an alignment sleeve holder capture gap therebetween.
The at least one latch gate is constructed and arranged to yield to the alignment sleeve holder as it is passed thereover and along the axis of the adapter body while being positioned therewithin, and to resiliently expand thereafter for retaining the alignment sleeve holder within the tubular body against the at least one annular stop in the described snap fit.
In a second embodiment, the alignment sleeve may comprise a stepped alignment sleeve for connecting a 2.5 millimeter diameter ferrule connector, for example an SC, ST(copyright), FC connector, to a smaller 1.25 millimeter diameter ferrule connector, namely an LC optical fiber connector. The stepped alignment sleeve takes the place of both of the aforementioned alignment sleeve holder and alignment sleeve as it performs both of the functions of the alignment sleeve and the sleeve holder both in this embodiment of the invention. The stepped alignment sleeve is also captured within the body of the adapter in a snap-fit for securing the stepped alignment sleeve within the tubular body of the adapter.
So constructed, the one-piece tubular optical fiber adapter of this invention allows for a first optical fiber connector selected from one of the group of optical fiber connectors consisting of an SC, ST(copyright), FC, and/or LC optical fiber connector to be connected to the first end of the tubular body, and also allows for a second optical fiber connector to be connected to the second end of the tubular body, where the second optical fiber connector is also selected from one of the group of optical fiber connectors consisting of an SC, ST(copyright), FC, and/or LC optical fiber connector.
The adapter of this invention is constructed and arranged to be received within a third snap fit within a mounting panel. Accordingly, the adapter is provided with at least one annular mounting flange formed on and extending at least partially about the exterior surface of the body and intermediate the ends thereof, with at least one resilient locking flange on the exterior surface of the body spaced from the mounting flange for defining a mounting panel capture gap therebetween. The locking flange is constructed and arranged to be urged inwardly toward the tubular body of the adapter as the adapter is passed through a mounting panel opening defined within the mounting panel, and to thereafter resiliently expand into a locking position for receiving the adapter therein in a snap fit.
It is, therefore, an object of the present invention to provide an improved one-piece optical fiber adapter for use with the known types of optical fiber connectors.
It is another object of the present invention to provide an improved one-piece optical fiber adapter which is simple in design and construction, is rugged and durable in use, and which is easy to use, install, and maintain in field applications.
It is to these objects, as well as to the other objects, features, and advantages of the present invention, which will become apparent upon reading the specification, when taken in conjunction with the accompanying drawings, to which this invention is directed.